Apparatus for preparing and dispensing mixtures of concrete and fibres

ABSTRACT

A mixing machine comprising a feed for at least one of the materials to be mixed which incorporates a rotatable scroll or worm and a hopper for a second material to be mixed, the discharge outlets of the or each of the feed scrolls or worms and of the hopper, communicating with a common rotating blending scroll or worm the hopper having a mesh or screen on which fibres can be loaded, either the hopper being reciprocable across the outlet to the feed scroll or the hopper and screen being relatively reciprocal.

May 27, 1975 United States Patent Harris et al.

[56] References Cited UNITED STATES PATENTS APPARATUS FOR PREPARING AND DISPENSING MIXTURES OF CONCRETE AND FIBRES Pence 'Carswell e X a S 72258 04555 99999 11111 66222 11 .75 3 6335 85773 58826 8257 00 2222 Primary ExaminerRobert W. Jenkins Attorney, Agent or Firm-Wood, Herron & Evans ABSTRACT A mixing machine comprising a feed for at least one of the materials to be mixed which incorporates a ro- [73] Assignee: Caledonian Mining Company Limited, Carlton-on-Trent, Newark, Nottinghamshire, England July 18, 1973 Appl. No.: 380,193

[22] Filed:

tatable scroll or worm and a hopper for a second material to be mixed, the discharge outlets of the or each of the feed scrolls or worms and of the hopper, com- [30] Foreign Application Priority Data municating with a common rotating blending scroll or worm the hopper having a mesh or screen on which July 22, 1972 United Kingdom... Sept. 26. l972 United Kingdom.... Sept. 29, 1972 United Kingdom....

fibres can be loaded, either the hopper being reciprocable across the outlet to the feed scroll or the hopper and screen being relatively reciprocal.

Dec. 5, 1972 United Kingdom.... Dec. 5, 1972 United Kingdom......,......,.

7 R 1 7 m64 7 5 33 2 O xnisi .904 a a 6 7 N ,6% H l w "5 2 "16 "W "W 9 W a nm m m "mr ".a uuez US/D L C 9 d5 Ld UmF 1.11. 218 555 PATENTEU MAY 2 7 I975 SHEET PATENTEU M27 1975 APPARATUS FOR PREPARING AND DISPENSING MIXTURES OF CONCRETE AND FIBRES This invention relates to concrete mixers and in particular to mixers for producing a mix for fibrous concrete i.e. concrete strengthened and improved by the addition of fibers.

Certain problems arise during the production of such a fibrous concrete mix as the fibres have to be evenly distributed throughout the mix in order for the maximum benefits to the concrete to be achieved. In particular the feed of the fibres into the mix has to be such that the fibres are not formed into balls rather than being evenly distributed throughout the mix.

It is therefore the general object of this invention to provide a mixing machine which overcomes the above problems and which produces a mix, in any desired proportions, of cement, aggregate and fibres.

A mixing machine in accordance with the invention comprises a feed for cement and aggregate incorporating a rotatable scroll or worm (preferably two, one for the cement and one for the aggregate) and a hopper for fibres, the discharge outlets of the or each of the feed scrolls or worms and of the fibre hopper communicating with a common rotatable blending scroll or worm, the fibre hopper having a mesh or screen on which fibres can be loaded either the hopper being reciprocal across the outlet to the feed scroll, or the hopper and screen having a relative reciprocation or vibration.

The use of a fibre hopper of this nature ensures that the fibres are fed evenly to the blending scroll and the danger of fibres of metal being attracted together by self-magnetism and being formed into balls is substantially reduced.

Conveniently the hopper is reciprocated over an outlet to the blending scroll, by a crank pivotally mounted to the hopper and to an eccentric point on a drive wheel.

The equipment is suitable for any form of fibre and the mesh of the hopper can be changed so that the size and shape of mesh is appropriate to the particular type of fibre and to the feed desired. Equally the feed of fibres may be varied by varying the stroke or frequency of reciprocation of the hopper, by varying the level of fibres maintained in the hopper during operation, or by varying the size of the outlet from the hopper.

Preferably fibres are fed to the hopper through a delivery tray and the tray may be vibrated to assist even flow of fibres. If the delivery tray is disposed over the mouth of the hopper then the level of fibres contained therein can be maintained substantially constant as the hopper reciprocates beneath the feed end of the tray.

The hopper may be mounted on wheels or on slides for reciprocal movement across its outlet port.

The fibres may be made of metal, plastics, glass or any other convenient material and may be made of any desired shape or configuration to suit the desired ultimate concrete mix.

The relative proportions of the ingredients of the mix may be varied by varying the speed of rotation of each feed scroll or worm or by adjusting the pitch or size of the flights of the feed scroll or worms.

The apparatus may also include a rotary blowing unit into which the common blending scroll or worm discharges and which comprises a venting hopper connected to a source of pressurised air and in which a rotor formed with a number of blades rotates. The mix on entering the hopper is rotated in the pockets formed between successive blades so that an even flow of material may be discharged from the hopper by the air pressure through an outlet port. This device helps to ensure an even supply of mix to a spray head connected to the outlet port and thus prevents surging.

The invention will now be further described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of an embodiment of mixing apparatus in accordance with the invention;

FIG. 2 is an exploded view corresponding to FIG. 1 but viewed from the other side of the apparatus;

FIG. 3 is a detail view of the feed scrolls or worms;

FIG. 4 is a detail view of the hopper for the fibres; and

FIG. 5 is a detail view of the rotary blowing device.

Referring to FIGS. 1 and 2 the apparatus comprises essentially a double hopper unit 2,4 to receive cement in one side 2 and aggregate in the other side 4 and a hopper 6 for fibres which are to be mixed into the cement/aggregate mix.

The hopper 2 for the cement opens into an outlet casing 8 through which a rotatable feed screw or worm 10 (see FIG. 3) extends. The feed screw is mounted in a tube 12 and in use is rotated so that cement is fed from the casing 8 along the tube to an outlet 14 which communicates with an inlet hole in a tubular casing 16 of a main blend scroll or worm l8 driven by a main motor 19.

Equally the sand (or other aggregate) hopper 4 communicates through a casing 20 with a feed screw 22 which on rotation acts to move the aggregate along a feed tube, similar to the tube 12, to the tube 14 so that a mix of cement and aggregate enters the casing for the main blend scroll or worm 18 this worm being rotatable to move the mix along the tubular casing 16 to an outlet 24.

The proportions of the cement and aggregate may be varied as desired in a number of different ways. For example the relative speeds of the two feed screws 10 and 22 may be altered by adjustment of gearing 25 in the drive for the screws. Alternatively each of the screws may be replaced bodily with a screw having different dimensions, different flights or a different pitch. In this way a very easy and yet precise control of the proportions of the mix can be achieved.

The fibre reinforcement is fed to the hopper 6 from a tray 26 the slope of which may be varied by adjusting the position of the supports 28 for one end of the tray on uprights 30. The tray is vibrated by means of a standard air vibrating unit 32 attached to the closed end of the tray so as to achieve an even feed of the fibres to the hopper.

Any form of fibre reinforcement may be used for example the reinforcement may be of glass, plastic or metal and can be of any desired shape. As an example the fibres may be of mild steel 1 inch long and 0.01 inch in diameter.

The hopper 6 contains a screen 34 and is provided with tubes 36 extending along each side thereof which engage over slide bars 38 connected to the frame of the machine (see FIG. 4). The hopper is arranged to be reciprocated over the inlet 40 of trunking 42 communicating with the casing 16 of the main feed screw downstream of the inlet 14. The reciprocation is achieved through a crank rod 44 pivotally attached to one end of the hopper 6 and mounted eccentrically at 46 to a driven crank wheel 48. Thus in use the hopper and its screen are reciprocated or vibrated on the slide bars, over the inlet to the casing of the main feed screw and this action has been found to achieve an even supply of fibres through the mesh 34 of the hopper on to the main blend screw.

It will be appreciated that the pitch or frequency of the reciprocation may be varied to suit different types and sizes of fibre as may the fineness and shape of the mesh of the screen 34. These variables also control the feed of fibres.

As the hopper is in fact reciprocated longitudinally relatively to the feed tray 26 the height of the pile of fibres in the hopper is controlled automatically new fibres spilling over from the end of the tray to replace fibres which have been fed to the blend screw. The feed of fibres from the hopper is also controlled by the height of the pile of fibres on the mesh.

The drive for the hopper reciprocation is provided with a manually operable clutch of standard type the control handle 50 of which (see FIG. 1) can be operated either to start or stop the supply of fibres as required independently of the supply of cement and aggregate.

The blend screw 18 which receives the fibres after it has received the concrete and aggregate acts to blend these ingredients together and to move them bodily along the casing 16 so that the mix emerges properly blended from the outlet 24.

From the outlet the mix falls through the inlet casing 52 of a rotary blowing unit generally indicated at 54.

The rotary unit has a venting hopper 56 (see FIG. 5) in which a horizontally mounted driven rotor 58 rotates, the blades 60 of the rotor defining a number of pockets which receive the mix from the inlet casing 52 and which transfers it to an outlet 62 at the bottom of the chamber. The rotor acts to ensure that an even flow of material reaches the outlet chamber 62 which is connected by a hose 64 to a supply of air under pressure and which communicates with an outlet hose 66 through which, in use, the mix is blown to a nozzle (not shown) where the mix is supplied with water and sprayed on to a surface to be concreted.

It will of course be appreciated that the mixer of this invention can be used to mix or blend any ingredients wet or dry and for example can be used to mix additives into material, one use would be the mixing of granular or powdered additives into cement.

Rather than supplying a dry mix to a spray head where it is mixed with water, a wet mix may be supplied and in this case the mixer may be fitted with a water metering device 70 which controls a supply of water to several injection ports 72 in the casing 16 of the blend screw. The water added in this way is blended with the cement aggregate and fibres to produce a wet concrete at the outlet 24 of the blend screw. When wet concrete is to be produced the unit 54 is not used and concrete is directed away from the inlet casing 52 thereof either by inserting a deflector plate (not shown) or by unbolting the unit.

We claim:

1. A mixing machine particularly adapted for use in the production of a fibrous mix, said machine compris- 1 a first hopper for a first feedstock,

a first feed screw disposed in fixed relation to said first hopper, said first feed screw being adapted to receive the first feedstock discharge fromsaid first hopper,

a blending scroll having first and second charging ports, said blending scroll being positioned relative to said first feed screw to receive through said first charging port the first feedstock discharge metered from said first feed screw, and

a fiber hopper having a screen fixed at the outlet thereof onto which fibers may be loaded, said hopper being positioned to discharge said fibers directly into said second charging port provided for said blending scroll, and said hopper being reciprocable relative to said second charging port for discharging fibers within said fiber hopper into said second charging port.

2. A mixing machine as set forth in claim 1, said machine further comprising,

a second hopper for a second feedstock, and

a second feed screw disposed in fixed relation to said second hopper, said second feed screw being adapted to receive the second feedstock discharge from said second hopper, and said second feed screw being positioned to meter the second feedstock into said firt charging port of said blending scroll.

3. A mixing machine as set forth in claim 2 wherein the rotational speeds of said two feed screws are adjustable relative one to the other, and are adjustable relative to said blending scroll.

4. A mixing machine as set forth in claim 1, said machine further including drive means interconnected with said fiber hopper for reciprocating said fiber hopper.

5. A mixing machine as set forth in claim 1, said second charging port being located downstream of said blending scroll relative to said first charging port.

6. A mixing machine as set forth in claim 5 including a delivery tray adapted to receive a supply of fibers,

.said delivery tray being cooperatively connected with said hopper to maintain the level of fibers in the hopper substantially constant during use of said machine, and

vibrator means secured to said delivery tray for feeding the fibers off said tray into said hopper.

7. A mixing machine as set forth in claim 1 including a rotary blower unit fixed relative to said blending scroll for receiving the fibrous mix discharged from said blending scroll, and

an air pressure port connected with said rotary blower unit, said air pressure port being adapted to receive pressurized air for ejecting the fibrous mix from the rotary blowing unit into a discharge hose without surging. 

1. A mixing machine particularly adapted for use in the production of a fibrous mix, said machine comprising, a first hopper for a first feedstock, a first feed screw disposed in fixed relation to said first hopper, said first feed screw being adapted to receive the first feedstock discharge from said first hopper, a blending scroll having first and second charging ports, said blending scroll being positioned relative to said first feed screw to receive through said first charging port the first feedstock discharge metered from said first feed screw, and a fiber hopper having a screen fixed at the outlet thereof onto which fibers may be loaded, said hopper being positioned to discharge said fibers directly into said second charging port provided for said blending scroll, and said hopper being reciprocable relative to said secOnd charging port for discharging fibers within said fiber hopper into said second charging port.
 2. A mixing machine as set forth in claim 1, said machine further comprising, a second hopper for a second feedstock, and a second feed screw disposed in fixed relation to said second hopper, said second feed screw being adapted to receive the second feedstock discharge from said second hopper, and said second feed screw being positioned to meter the second feedstock into said firt charging port of said blending scroll.
 3. A mixing machine as set forth in claim 2 wherein the rotational speeds of said two feed screws are adjustable relative one to the other, and are adjustable relative to said blending scroll.
 4. A mixing machine as set forth in claim 1, said machine further including drive means interconnected with said fiber hopper for reciprocating said fiber hopper.
 5. A mixing machine as set forth in claim 1, said second charging port being located downstream of said blending scroll relative to said first charging port.
 6. A mixing machine as set forth in claim 5 including a delivery tray adapted to receive a supply of fibers, said delivery tray being cooperatively connected with said hopper to maintain the level of fibers in the hopper substantially constant during use of said machine, and vibrator means secured to said delivery tray for feeding the fibers off said tray into said hopper.
 7. A mixing machine as set forth in claim 1 including a rotary blower unit fixed relative to said blending scroll for receiving the fibrous mix discharged from said blending scroll, and an air pressure port connected with said rotary blower unit, said air pressure port being adapted to receive pressurized air for ejecting the fibrous mix from the rotary blowing unit into a discharge hose without surging. 